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UPDATES : tripath ta2022 amp with 6N11 tube preamp and pcm1798 dac

The finished amp in its white lacquered box , coupled with my great Siemens drive

I think the tripath ta2022 is the best D-Class amp available. I already assembled one with an opamp preamp, so I had to try one with a tube preamp, here in a complete board with chinese 6N11. Here is the board :

When I first plug it, one problem occurred : there was a loud buzz in the spealers. From my experience, this had to do with the tube power supply filtering. The filaments are on DC and correctly filtered on the right bottom of the pic with 1200MF good caps so it had to be the 'high' voltage.
This 35v 'high' voltage was filtered by 2 surface mounted 100MF caps. Look like the perfect suspects.

They were guilty . A change for 1000MF good electrolytics fixed the problem.
Well, there is still a small wee hum, but it really is subtle for this kind of simple circuit.
You could argue a 35v fueled tube in front of this great chip is placebo. Well, yes and no...of course I would need much more voltage to be sure to 'hear' the tube, but it somehow presents the signal with a consistency only tube can bring, which is kind of important with D-Class amp which are VERY sensitive to input voltage. And the final tone is really great for such a cheap board.

While at it, I decided to complete this stereo amp with a 24/192 dac which was sleeping in a box since I ordered it. It's a very good pcm1798. At first , I wanted to remove the opamps as usual , but it turned out to make too much noise when changing inputs on the amps.
So I put them back, for sake of my speakers..

The final set up : ta2022 amp with onboard 6N11 preamp fueled by big toroid transformer, and the pcm1798 dac with psu and small transformer---here hidden with brown isolator as 230v volts pins were apparent.
This amp will be used for monitoring, coupled with Siemens drive plugged directly in spdif and telefunken tlx33 speakers.
And I still get 3 free inputs !

I am still amazed by the Siemens as a transport...this simple machine did not even had a spdif output in the 1st place...I had to build it from this simple yellow wire going from the sony dsp chip to the disconnected left output.

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